Device for Casting

ABSTRACT

The present invention is a casting machine for casting parts in a mold out of a metal using a metal feed stock. The machine includes a processing cylinder formed in a thermally conductive block, said processing cylinder having a processing chamber and opposite first and second ends, the first end of the processing cylinder being configured to receive the metal feed stock. The machine further includes an injector cylinder formed in the thermally conductive block adjacent the processing cylinder, the injector cylinder having a shooting pot coupled to the second end of the processing cylinder by a passage configured to permit feed stock to pass from the processing cylinder into the shooting pot, a nozzle coupled to the injector cylinder configured to couple to the mold. The device includes a processing drive for driving the feed stock from the first end of the processing cylinder through the passage into the shooting pot and a heater thermally coupled to the processing cylinder. The heater and processing cylinder are configured to heat the feed stock such that the feed stock becomes progressively more liquid as it passes from the first to the second end of the processing cylinder. The machine further includes an injector plunger coupled to an injector actuator for driving the plunger sufficiently to force the metal from the shooting pot through the nozzle and into the mold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application a continuation of U.S. application Ser. No. 12/098,368filed on Apr. 4, 2008 which claims priority from U.S. ProvisionalApplication No. 60/907,533 filed on Apr. 6, 2007 and U.S. ProvisionalApplication No. 60/935,561 filed on Aug. 20, 2007 all of which areincorporated herein by reference.

FIELD OF THE INVENTION

The invention relates generally to devices for casting or molding parts.

BACKGROUND OF THE INVENTION

It is a trend to increase the strength and reduce the weight of allkinds of transportation vehicles (bikes, motorbikes, cars, trucks,aircraft, space shuttle and others). With reduced weight, reduced fuelconsumption and reduced gas emissions to follow. Today, automobilemanufacturers are using more and more plastics, but plastic's strengthto weight ratio is low when compared to light metals like aluminum, andin particular magnesium. Plastic also has the disadvantage of beingdifficult to recycle and separate it from other materials inautomobiles. Light alloy parts in cars are easy to separate forrecycling and materials are generally environmentally friendly withlower energy impact.

Prior art in the field of light alloy castings is based on the premisethat a melting pot is required for melting material, after which themolten material is transported into the die-casting machine. Basically,in prior art, the die-casting process is accomplished by meltingmaterial in big pot, transferring the material into a machine (manuallyor by robot) and injecting this molten material into a cavity with highforce and low to high speed. Considering the fact that in prior artmolten material resides in a big pot, it is a requirement of the processthat the molten material is overheated (superheated). For magnesium thismelt temperature is 700°-780° C. Superheated melting is done to overcomecooling losses encountered in the process of melt transfer from pot tothe die-casting machine. Intense energy requirements for this processare a major drawback for this technology. Furthermore, handling the meltin the manufacturing process is riddled with losses and meltcontamination. Intense oxidation of the melt results in poor castings.Injection of material into the cavity requires high speed, andturbulence from the process often results in extensive inclusions in thecastings. Defects of this nature are detrimental for applications in theautomotive industry, particularly for castings related to vehiclesafety. From the above brief description of the current state of the artwe can see a need for more efficient machines that will reduce energyconsumption to a minimum and totally eliminate Green House Gas (GHG)use.

Die-casting is a manufacturing process used to produce a part innear-net shape with high dimensional accuracy and a good surface finishin a short cycle time. The casting industry branched in two directions:Melt processing, where hot and cold chamber casting dominate, and semisolid slurry processing where Rheomolding and Thixomolding® routes havebeen adopted. Cornell research foundation's U.S. Pat. No. 5,501,266discloses a process called Rheomolding. Superheated liquid metalsupplied from outside is cooled into a semi-solid state in the barrel ofa special vertical-injection molding machine, with the growing dendritesof the solid state broken into small and nearly spherical particles bythe shearing force generated by the screw and barrel. It was said thatthis process can produce net-shape metal parts at a lower cost but thishas not been the case under real market conditions. These machines arevery expensive and complex, difficult to operate and support. TheRheomolding route has hot been often used. The Thixomolding® route, alsoknown as semi-solid casting or molding (as terms used in the plasticsindustry) has been more widely adopted.

Conventional die casting apparatuses are classified into cold chamberand hot chamber. The cold chamber die-casting process uses a superheatedmolten metal alloy. Referring to FIG. 14 we can see a cold chamber diecasting machine. Molten alloy (magnesium, aluminum or zinc) is injectedinto a closed metal die under high pressure by way of a high-speed ram.The alloy is driven through the feed system of the die, while air fromthe mold escapes through vents. There must be enough metal to overflowthe cavity, such that a complete part will be cast. Once full, theinjection pressure on the mold is increased during solidification. Thepressure is increased during solidification to reduce porosity due toshrinkage. To complete this path from the molten pot to the die cavitywithout starting to solidify, the melt must be superheated up to 100° C.above liquidus temperature. As the metal dies (or molds, as they areknown in the plastics industry) are cooled, molten metal gets solidifiedinto a predetermined shape. Once sufficiently cooled, the part isremoved from the die.

The second well known process for casting light metal alloys is the hotchamber die casting method. Referring to FIG. 15, we can see a hotchamber die casting machine. The pressure chamber (cylinder) and theplunger are submerged in the molten metal in the pot (crucible). Hotchamber die casting means, compared to cold chamber, that the moltenmetal is transported directly into the die via a heated channel called a“gooseneck”, thus minimizing heat loss.

As one can appreciate, both of the above-mentioned processes use meltthat is heated to higher than optimal casting temperatures to compensatefor heat losses. Hot chamber die-casting does not require the melt to beas hot as in cold chamber. To reduce heat losses of the melt, asignificant portion of the injection system is submerged in molten metalat all times. The benefit of hot chamber die-casting is that melttravels a short distance and the cycle time is reduced. However, hightemperature and continued exposure to aggressive melt creates severematerial deterioration problems. As is well known, both processes sufferpoor reliability due to lack of suitable materials for melt containmentand no means to overcome melt corrosion and high pressure and highapplicable temperature. Both processes suffer from material shrinkage inthe cast parts, from 5-15%. High injection rates also cause gases to bemixed into the melt and becoming trapped in the part. Porosity is thebiggest problem for a part's structural integrity. Molded metallic partswith high porosity are not desirable because of their reduced mechanicalstrength. It is because of this that it is very difficult to accuratelydimension conventionally die cast parts, and it is even more difficultto maintain the dimensions throughout life cycle of the part. Therefore,the quality of the components made on these machines is generally poorand often does not meet the stricter requirements for the automobileindustry. Because the scrap rates are high, die casters continue to usemelt pots, as this allows the immediate remelting of the scrap parts.Unfortunately, producing scrap still requires energy to remelt the part,and cover gases, such as sulfur hexafluoridc (SF₆) and carbon dioxide(CO₂) are wasted. Both gases have a significant environmental impact.

Besides environmental pollution, cast parts made from super heated meltare often plagued by entrapped porosities and inclusions created bylarge amounts of shrinkage due to rapid material cooling fromsuperheated melt to solid near net shape parts.

FIG. 16 shows an injection molding apparatus adopted from thermoplasticprocessing. This apparatus has a composite cylinder with an innerdiameter of 50 to 200 mm and a length, of approximately 2 to 5 m. Aspecially devised drive is coupled to a retractable helical screwdesigned to transport the alloy material along the cylinder. The heat tomelt the metal alloy is provided by a series of heated zones arrangedalong the cylinder. The forward end of the cylinder is closed by thecylinder cover but allows material transfer into a nozzle portion at thedistal end of the cylinder. A specially designed check valve is placedat the forward end of the screw to facilitate injection of the moltenslurry into the mold. In the art of plastic injection molding thecylinder is called a barrel and whole assembly is well known as anextruder. The cylinder can be a monolithic tube or made from Inconel 718with specially fitted Stellite liner to reduce corrosion. Stellite is aCobalt alloy with specific corrosion and abrasion properties suitable tocontain and convey molten magnesium.

In this process, solid chips of alloy material are supplied to theinjection molding apparatus through a feeder portion often called ahopper. The size of the chips is approximately 2-3 mm in diameter andgenerally is no longer than 10-12 mm. The chips are produced fromStandard die casting alloys in ingot form. The ingots are chipped tosize by a separate machine designed for this purpose. The comminutedchips are fed into a hopper and further processed in the injectionmolding extruder into a supposedly preferential state called aslurry-like melt, which is, in its best form, in a partially moltenstate. The injection screw shears the melt and pushes the melt forwardover a check valve on the distal end of the extruder and is subsequentlyinjected into a closed and clamped injection mold. The machine nozzledispenses the thixotropic slurry into a mold portion of the SSIMapparatus, often called a sprue. The sprue is a part of the moldassembly not described in this enclosure.

There is a clear advantage of the slurry (Thixomolding®) process overthe die casting process in the fact that process does not use SF₆ covergas. Small amounts of argon gas are used to protect the melt fromoxidation. Argon is heavier than air and tends to stay close to earthand gets dissolved and returned to air naturally. However, one familiarwith this state of the art will appreciate that the thixomolding® andsimilar semi-solid processes are complex and require a very long meltpassageway. All of these methods and processes are carried out within asingle cylindrical housing. Manufacturing suitable barrels is a tediousand requires expensive alloys and processes. As a result only a fewsuppliers are able to produce composite barrels with Stellite liners inInconel housings with the dimensional requirements for large throughputfor any serious part molding using these methods.

Very accurate control of die process temperature is essential forsuccessful and repeatable molding of good parts with injection moldingmethods disclosed above. It is very difficult to control all of theprocess parameters within a single cylindrical housing, particularlytemperature, shot volume, pressure, cycle time, etc., and as a result,inconsistent characteristics of the molded metallic parts are produced.As a consequence, if a molded metallic part of undesired characteristicsis produced by a semi solid slurry molding machine, recycling of thedefective part is not possible. Metal parts molded by injection moldingmachines with high solid contents may have an uneven surface. Such metalparts may require further processing before they can be painted.Finally, the above mentioned injection molding process is complex andexpensive to manufacture, and is plagued by the reliability of itsmachine parts. Further, it lacks the wide operating window and stabilitythat are required for a viable manufacturing process.

One skilled in the art can recognize the complexities involved in thedie casting process and structures (cold and hot chamber) as well as inthe molding process and structures (Rheomolding and Thixomolding®). Bothprocessing routes are largely unreliable and suffer from a lack ofconsistency from shot to shot and part to part. There is a need for anew and simpler structure with a stable processing window and withoutthe use of SF₆ cover gas. Furthermore, molds for above machines aremostly cooled by oil. Oil is environmentally unfriendly and there is aneed to eliminate the oil for any kind of cooling on the machine.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a casting machinehaving a simple design which is economic and practical to reproduce andyet overcomes the disadvantages of the prior art while enabling thecasting of parts having very few defects. A casting machine made inaccordance with one aspect of the present invention includes aprocessing cylinder formed in a thermally conductive block, saidprocessing cylinder having a processing chamber and opposite first andsecond ends, the first end of the processing cylinder being configuredto receive the metal feed stock. The machine further includes aninjector cylinder formed in the thermally conductive block adjacent theprocessing cylinder, the injector cylinder having a shooting pot coupledto the second end of the processing cylinder by a passage configured topermit feed stock to pass from the processing cylinder into the shootingpot, a nozzle coupled to the injector cylinder configured to couple tothe mold. The device includes a processing drive for driving the feedstock from the first end of the processing cylinder through the passageinto the shooting pot and a heater thermally coupled to the processingcylinder. The heater and processing cylinder are configured to heat thefeed stock such that the feed stock becomes progressively more liquid asit passes from the first to the second end of the processing cylinder.The machine further includes an injector plunger coupled to an injectoractuator for driving the plunger sufficiently to force the metal fromthe shooting pot through the nozzle and into the mold.

A casting machine made in accordance with another aspect of the presentinvention includes a thermally conductive block having a processingcylinder and an adjacent injector cylinder formed therein. Theprocessing cylinder has opposite first and second ends, the first endconfigured to receive casting feed stock. The block is thermally coupledto a heater. The heater, block and processing cylinder are configured toheat the feed stock such that the feed stock becomes progressively moreliquid as it passes from the first to the second end of the processingcylinder. The injector cylinder has a shooting pot and an injectorplunger coupled to a nozzle, the shooting pot being coupled to thesecond end of the feed stock processing cylinder by a passage. Thepassage is configured to permit the one way movement of heated feedstock from the processing cylinder into the shooting pot. The injectorplunger is configured to inject the heated feed stock through the nozzleand into the mold.

A casting machine made in accordance with another aspect of the presentinvention includes a mold having a plurality of mold portions, each moldportion configured to mold a different portion of the part. The castingmachine further includes a plurality of molding units, each molding unitbeing coupled to one of said portions for molding said portion. Eachmolding unit includes a thermally conductive block with a processingcylinder formed therein, said processing cylinder having opposite firstand second ends, the first end configured to receive the feed stock. Theblock is thermally coupled to a heater, which together with the blockand the processing cylinder are configured to heat the feed stock suchthat the feed stock becomes progressively more liquid as it passes fromthe first to the second end of the processing cylinder. The moldingunites further include an injector cylinder formed in the block adjacentthe processing cylinder, the injector cylinder having a shooting pot, aninjector plunger and a nozzle, the nozzle being coupled to the moldportion. The shooting pot is coupled to the second end of the feed stockprocessing cylinder by a passage configured to permit the movement ofheated feed stock from the processing cylinder into the shooting pot.The injector plunger is configured to inject the heated feed stockthrough the nozzle and into the mold.

With the foregoing in view, and other advantages as will become apparentto those skilled in the art to which this invention relates as thisspecification proceeds, the invention is herein described by referenceto the accompanying drawings forming a part hereof, which includes adescription of the preferred typical embodiment of the principles of thepresent invention.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a casting machine made in accordancewith the present invention and showing the injector assembly.

FIG. 2 is an aligned section view of the injector assembly shown in FIG.1 through the tie rods and feed port and showing the connectinggalleries for flow of the material being processed.

FIG. 3 is an alternative section view of the injector assembly of FIG. 1showing the load path through the structure.

FIG. 4 is a view showing the drive mechanism for the distributor.

FIGS. 5 though 9 are a series of sectional views of the casting machineshown in FIG. 1 and showing the sequence of operation of the internalcomponents of the injector.

FIGS. 10 is a perspective view of an alternate embodiment of the presentinvention.

FIG. 11 is a perspective view of an alternate embodiment of the presentinvention.

FIG. 12 is a perspective view of the casting machine shown in FIG. 1coupled to a feed stock pre-conditioning system.

FIG. 13 shows a mold heating and cooling plate.

FIGS. 14 to 16 show prior art casting machines.

FIG. 17 is a perspective view of a portion of the casting machine shownin FIG. 1 and showing the interaction of the distributor vanes with theprocessing plungers.

FIG. 18 is a perspective view of an alternate embodiment of the presentinvention showing two casting units made in accordance with the presentinvention combined to mold a large part.

In the drawings like characters of reference indicate correspondingparts in the different figures.

DETAILED DESCRIPTION OF THE INVENTION

In the description of the preferred embodiment which follows, the castpart is preferably produced from magnesium alloy, preferably AZ91D, in anovel machine that will be illustrated and described below. Thisapparatus and method of casting high integrity parts is not limited tomagnesium alloys and is equally applicable to any other type of metal,such as aluminum (Al), zinc alloys and any other alloy suitable forsemisolid or liquidus processing. A high integrity part is understood tobe One with minimal or no porosity or inclusions and metallurgicalcomposition with a preferred dendrites free structure. Furthermore,specific temperature ranges used in the description will be relevant formagnesium alloy, but do not preclude the use of other alloys. Themaximum operating temperature for this invention is preferably 700° C.,however the actual operating temperature is limited only by the currentavailability of special materials capable of withstanding the harshconditions imposed by liquid alloys. Other raw material that can besuccessfully processed according to this invention could potentiallycome from materials with much higher melt temperatures but when combinedwith at least one additional metallic alloy or at least one ceramiccomposition and/or structure will be processable at temperatures lessthan 700° C. As well, the present invention may find use in othermolding applications such as thermosets, liquid metal, composites,powder metal molding and/or other process where processing temperaturedoes not exceed 700° C.

The above-mentioned raw materials can be used in various forms andphysical shapes where the only limitation is that they are in apreferential form that maximizes outside surface of the forms formaximum heat uptake. Heat energy is absorbed by conduction, and theamount of heat is proportional to the surface temperature of the bulkmaterial. The preferential form of the material would be one thatabsorbs a large quantity of heat as quickly as possible at a uniformrate through the total bulk of the material. Reducing the size of theparticles of the feedstock can artificially increase the surface area.Preferred particle shapes are formed of prolate spheroid (football likeshapes) where polar diameter is 6-16 mm and equatorial diameter is 2-4mm. This form and shape or its approximations have relatively largesurface area and absorbs heat optimally, yet it flows easily throughpassages or melt channels and does not clog them. While powder materialshave the extreme values of available surface, this feedstock is notrecommended due to spontaneous combustion hazards and the notorioustendency to conglomerate, as well as the inability to heat byconduction.

Referring firstly to FIG. 2, the present invention is a casting machineunit for metal alloys and is shown generally as item 200, which has athermally conductive block 10 (also called a processing barrel) having aplurality of processing cylinders 11 formed therein adjacent to andsurrounding a centrally positioned injection cylinder 250 which is alsoformed in the block (processing barrel) 10. Each of the processingcylinders 11 have opposite first ends 260 and second ends 262. first end260 is configured to receive the feed stock (not shown). Second end 262is coupled to shooting pot 19 of injector cylinder 250 by passage 13.Processing plungers (also called stuffer rods) 84 are provided to drivethe feed stock from first end 260 towards second end 262. Heater 50 iscoupled to block (barrel) 10 and provides sufficient heat toprogressively melt the feed stock as it passes from ends 260 to 262 suchthat the feed stock becomes progressively more liquid as it passes toend 262. Preferably, heater 50 and cylinders 11 are shaped such that thefeed stock is not completely melted (i.e. liquidous) when it exits end262 and passes to shooting pot 19. Plunger (sniffer rod) 84 is coupledto a processing drive 26 (see FIG. 1) which is configured to urge thefeed stock sufficiently such that it passes into shooting pot 19. Thefeed stock may, under the right circumstances, be driven simply by theforce of gravity; however, the processing drive preferably consists ofan actuator of some type such as a pneumatic of hydraulic piston.Processing plunger 20 is likewise coupled to an injector actuator ordrive 22 which is configured to force the feed stock in shooting pot 19through nozzle 12 a and into the mold (not shown).

Referring now to FIG. 1, this figure shows the general externalconfiguration of the device. Tie rods 42 and nuts 44 connect the upperplaten 56 to an upper plate 34 which is connected to cylinders 22, 24and 26. Cylinder 22 contains piston 28 which is connected to plunger 20.This arrangement provides vertical movement of the plunger 20.

Cylinders 26 contain pistons 32 which are connected to a first member(also called stuffer plate) 80 by nuts 82. The stuffer plate 80 isconnected to the processing cylinder plungers (also called stuffer rods)84 with screws 78. This arrangement provides vertical movement of thestuffer rods 84. Cylinders 24 contain pistons 30 which are connected tothe top plate (or cap) 36. This arrangement provides a clamping forcewhich keeps the stack of hot components loaded vertically in compressionduring the operation of the machine and eliminates the requirement forhigh-temperature fasteners. Lower platen 58 holds the lower half of themold 62 and can move downwards to open the mold and allow removal of thecast part. Feed housing 64 has an opening into which the feedstock issupplied. Insulated blanket 48 prevents excessive heat loss from the hotinternal components to the rest of the machine or the environment.

Referring now to FIG. 2, the vertically oriented processing barrel 10receives solid metal feedstock from a port 63 in a feed housing 64,melts the metal feedstock and injects it using a plunger 20 into a mold60 and 62 to create a solid metal part. Starting with the feedstockentering the port 63 in the feed housing 64, the feedstock isdistributed across the upper surface of the processing barrel 10 using arotating distributor 66. The feedstock enters one or more vertical holesor cavities 11 in the processing barrel 10. Motor 88 drives a pinion 86which meshes with and drives gear 68. Gear 68 is attached to therotating distributor 66 using screws 70. Distributor 66 can be stoppedin a position where slots 67 in the distributor 66 align with the holes11 in the processing barrel 10.

One or more stuffer rods 84 reciprocate vertically through the slots 67in the distributor 66 and inside the holes 11 in the processing barrel10 to push the feedstock downward into the processing barrel 10. When inthe uppermost position, the stuffer rods 84 are clear of the distributor66 such that the distributor 66 can rotate.

The processing barrel 10 is heated by heaters 50. Excessive heat loss tothe environment and adjacent machine components is prevented by aninsulating blanket 48. The feedstock is pushed by the stuffer rods 84such that it makes contact with the walls of the holes 11 in theprocessing barrel 10 and is melted either partially or fully. Theresulting slurry is pushed by the stuffer rods 84 through a groove orcavity 13 in the upper surface of the cap 12 which opens a check valve16 off its seat 14 allowing the slurry to enter the shooting pot 19beneath the plunger 20. The plunger 20 has scaling rings 90 whichprevent most of the material from flowing upwards past the rings 90. Anymaterial which does leak past the sealing rings 90 is returned to theexternal holes 11 in the processing barrel 10 through angled drillings15. The plunger 20 is forced downwards at high speed by the piston 28which moves inside cylinder 22. The pressure of the slurry and gravityclose the check valve 16 against seat 14 which prevents the pressurizedslurry from returning into the stuffer bores 11 through cavity 13. Thepressurized slurry is forced from the shooting pot 19 of the processingbarrel 10 through the cap 12 and the nozzle 21 into the mold 60 and 62which is held between an upper platen 56 and a lower platen 58. The moldremoves heat from the slurry such that a solid part is cast. A heater 50maintains the temperature of the nozzle 21 so that the slurry does notsolidify inside it. Another heater 52 maintains the temperature of thenozzle 21 when it is engaged with die mold 60 such that the slurry doesnot solidify inside the nozzle 21. Tie rods 42 and nuts 44 couple theupper platen 56 to the upper plate 34 which provides a suitably rigidbase for the cylinders 22.

Referring now to FIG. 3, tie rods 42 and nuts 44 couple the upper platen56 to the upper plate 34 which provides a suitably rigid base for thecylinders 22 and 24. Pistons 30 push down on top plate 36. Top plate 36pushes on the upper ring 38 which is designed to minimize heat flow fromthe hot components underneath to the cooler top plate 36. The outer edgeof the upper ring 38 has a retainer 74 which holds a bearing 72 whichsupports the distributor 66 and allows it to rotate. Screws 76 clamp thebearing 72 between the upper ring 38 and the retainer 74. A scraper ring40 is clamped between the upper surface of the processing barrel 10 andthe upper ring 38. The scraper ring 40 removes any material which mayhave leaked past the sealing rings 90 and has become stuck to theplunger 20. This material is returned to the external holes in theprocessing barrel 10 through angled drillings 15. A sealing ring 18prevents slurry from escaping to the outside through the joint betweenthe cap 12 and the processing barrel 10. Leakage from the high pressurezone in the center bore of the processing barrel through the jointbetween the processing barrel 10 and the cap 12 is minimized by the highclamping forces provided by the clamping cylinders 24 and pistons 30.Any leakage from this joint simply mixes with the low-pressure slurry inthe adjacent gallery in the cap 12.

FIG. 4 shows a little more clearly the motor 88 which drives a pinion 86which meshes with and drives gear 68. FIG. 17 shows how stuffer rods 84pass through openings 67 in distributor member 66 and between projectingfingers 67 a.

FIGS. 5 through 9 show the sequence of operation of the devices. In FIG.5, the components are positioned such that the slurry is ready to beinjected into the mold 60 and 62 by the plunger 20. Nozzle ports (portsin the lower end of cap 12) are aligned with channels in the mold 60 and62 to accept the slurry. At this point the slurry inside the nozzleports (lower thin part of cap 12) is in a semi-solid state whichprevents premature flow into the mold.

In FIG. 6, piston 24 pushes plunger 20 downwards to inject the slurryinto the mold 60 and 62. The pressure of the slurry overcomes theresistance to flow through the nozzle ports (ports in the cap 12).During or following the inject cycle, stuffer rods 84 may start to moveupwards in preparation for receiving more solid feedstock through thefeed housing 64. Once the part has been cast, it freezes off formingplugs of solidified material in the nozzle ports.

In FIG. 7, the upper mold half 60, lower mold half 62 and lower platen58 move downward by the mold actuator (not shown) to a position wherethe nozzle ports are blocked by the mold upper half 60. This shears offthe plugs in the nozzle and prevents leakage through those ports.

In FIG. 8, the stuffer rods 84 are in the uppermost position whichallows distributor ring 66 to rotate, distributing feedstock from thefeed housing 64 into the top chamber of the processing barrel 10, themold lower half 62, concurrently opens fully to allow the cast part tobe extracted.

In FIG. 9, the stuffer rods 84 are moving downward to push feedstockinto the external cavities in processing barrel 10. Feedstock which hasalready melted fully or partially is forced through a channel in theaccumulation chamber (the upper surface of cap 12) through check valve16 into the shooting pot (the cavity below the plunger 20), forcing theplunger to move upwards. Once the stuffer rods 84 stop their downwardmovement, check valve 16 closes by gravity, preventing back-flow. Thiscycle can be repeated two or more times during each molding cycle toaccumulate sufficient slurry to form the next cast part.

Referring to FIGS. 10 and 11, in addition to the preferred embodimentdiscussed above, other possible embodiments of this invention arepossible which incorporate a thermally conductive processing barrel andstuffer cavities. In FIG. 10 illustrates one such embodiment 100 whichconsists of a concentric structure of a processing barrel 110. In thecentre is plunger cavity 112 with shooting pot 114. The processingchamber (or cylinder) 116 is around the injector barrel 110 and coupledto the shooting pot by passage 115. The heaters (not shown) are mountedon the outside wall of the processing cylinder.

In FIG. 11, an alternate embodiment 120 is illustrated which includesthe injector cylinder 111 with plunger and shooting pot is in thecentre. The heaters (not shown) are mounted on the outside wall of theinjector barrel. External stuffer (processing) cylinders 122 arepositioned around the injector barrel and each of them is heatedseparately. On the bottom of the external stuffer cavity slurry atransfer valve can be mounted. Usually the bottom is directly connectedto the accumulation chamber.

Referring now to FIG. 12, the feedstock conditioner 130 a is used toeliminate moisture and oxygen molecules attached to the particles offeedstock material. Preferred feedstock material is prolate spheroid(football like shape) but similar elongated cylinders or cigar shapedforms are also useable. For practicality reasons these ideally suitedshapes are an approximation of the elongated chopped spaghetti chips.Solid ingots could further be cut or machined or chopped into suitablydesigned forms that closely resemble preferred shapes.

This invention is not limited by the type of feedstock used. Thisinvention only requires comminuted material due to the need for shortresidence time processing to preserve the preferred metallurgicalcharacteristics of the feedstock. The preferred embodiment of thisinvention is to preserve all inherited feedstock properties and notchange them. The preferred embodiment of the feedstock conditioner 130 aheats the feedstock to a maximum temperature of 425° C. for magnesium.The heat energy used by condition 130 a conies from cooling mold 60 viaa mold cooler 62. Mold cooler 62 is coupled to conditioner 130 a bypipes 101 a, pump 102, pipe 100 and return pipe 101. A suitable heattransfer medium (or coolant) flows through the cooler, pipes and pump.Heat removed from the cast part is conductively brought into thefeedstock conditioner, and under an atmosphere of hot argon, properpurging of the feedstock material is accomplished. So, high energyefficiency is achieved by this invention when energy added to meltduring viscosity modulation is then recovered and used for materialpre-heating, therefore returned back into the process and not rejectedinto the atmosphere as is done in earlier disclosures cited here forreference. Use of the heated argon in the preferred embodimentfacilitates a bubbling effect of the feedstock where the feedstockbehaves as a liquid for uniform heat transfer by convection and inaddition to conduction. In addition to recovered energy, additionalelectrical energy may be added to this part of the process.

Looking further in FIG. 12, once feedstock conditioning is completed,the feedstock is advanced into a feedstock distributor via tube 131 bygravity or by way of powered auger metering (not shown).

Referring now to FIG. 13, the mold heating/cooling plates are made toremove heat from the castings. Heating/cooling plates are attached tothe mold to maintain optimal mold temperature. The mold is heated tooptimum temperature using an electric heater element (not shown) placedinto the heater channel 5. When a part is cast, heat is imparted to themold and the cooling plate. Atomized water (80% air and 20% water) isinjected into the cooling channels 1 through nozzles 4 inserted intoholes 2. As the atomized water comes in contact with the walls of thechannels, the water droplets (smaller than 200 microns and preferablybetween 25 to 75 microns) change from liquid to gas, absorbing heat. Thegaseous water is then forced to exit the cooling plate through theexhaust port 3 using compressed air from the spray nozzle. When the moldhas reached the desired temperature, the spray is turned off andcompressed air is used to chase any remaining steam out. The heaterplate sits on the top of the cooling plate and faces the mold insert.The cooling-heating plate has one side dedicated to cooling and on theother side facing the cavity insert electrical heaters are inserted intogrooves. At least one temperature feedback device is attached to theheating and/or cooling side of the plate to effectively and controllablyregulate the temperature of the plate. Experimental testing andmeasurements discovered that large amounts of heat can be removed fromthe plate by mixing air with atomized water. High-pressure air isinjected in the pressurized water to generate a fine mist like coolingmedium suitably applied in a controllable manner to the cooling side ofthe plate. While water-cooling is well used for cooling molds, speciallyprepared water-air mixtures have not been used for cooling in partcasting operations. It is not known to these inventors that any suchapplications are used in the die-casting industry using water airmixture for mold/die cooling. It is a surprising discovery that the airwater mixture in this preferred embodiment is never sprayed into aclosed cavity of the cooling plate created in a specific pattern toremove heat. The preferred pattern of the engraving into the coolingplate is diamond shape islands with rectangular channels in between.This pattern provides the best heat removal rate. The specificallydeveloped pattern is optimized to increase surface heat removal. Almostwithout exception hot oil is used to cool and heat molds. Hot oil has alow flash point and in combination with magnesium explodes in fire.Additionally, oil is not a good thermal conductor of heat and is veryinefficient as either a cooling or heating medium. Because of this,expensive and large heat exchangers are used to heat a large volume ofoil and for removing heat from the oil, water is then used. As well,often at such high operating temperatures oil fittings leak and constantpotential for environmental contamination exists.

Referring now to FIG. 18, it is possible to use the compact castingmachine to mold (or cast) large parts using a plurality of smallermolding (or casting) units. A modular molding machine made in accordancewith one aspect of this invention is shown generally as item 160 andconsists of a plurality (in this case two) of molding units 162. Moldingunits 162 are each identical in every way to casting machine 200 shownin FIG. 1 and discussed above. The molding units 162 each have a moldingnozzle 21 which is coupled to a different portion of mold 130. Eachportion of mold 130 casts (or molds) a different portion of the finishedpart (not shown), therefore each molding unit 162 casts (or molds) adifferent portion of the part.

When the mold opens, the cast part is attached to the core portion ofthe mold and is presented to a robot for removal. Suitably placedejector push rods facilitate removal of the casting. It is well known inthe art that the process of part removal can be done with variousautomated machines such as robot devices. The cavity inserts moldingsurfaces are conditioned for the next casting cycle by applying suitablemeans of mold release or mold lubricant by automatic means.

The present invention has several advantages over the prior art. Thearrangement of processing cylinder and shooting pot adjacent to oneanother in the same physical block of material offers a number ofadvantages compared with the prior art. Firstly, heat is effectivelytransferred from the heaters through the block to the shooting pot.Additional heaters are not required to maintain the shooting pottemperature as they are in a thixomolding machine. Also, the additionalwall thickness of the cylinder provides improved resistance to crackingof the inner wall of the shooting pot due to the high internal stressesat that location. Also, any minor leaks from the high-pressure area ofthe shooting pot cannot escape directly into the environment as in athixomolding machine, the leakage simply returns to the low-pressurechamber of the processing cylinder. Furthermore, the overall dimensionof this cylinder arrangement is extremely compact compared with theprior art. In addition, the vertical orientation of the device ensuresthat the liquid or semi-solid material being processed does notcontaminate the solid portion of the feed material when the machine isnot in operation. Also, the multiple processing cylinders offerincreased surface area for conduction of heat to the feedstock. Further,the diameter of these cylinders can be independently dimensioned to thatof the shooting pot, unlike a typical thixomolding machine where thecylinder is one diameter. And finally, this compact, single blockconstruction is less expensive to manufacture than the equivalentfunctional assemblies of hot-chamber die casting or thixomoldingmachines.

A specific embodiment of the present invention has been disclosed;however, several variations of the disclosed embodiment could beenvisioned as within the scope of this invention. It is to be understoodthat the present invention is not limited to the embodiments describedabove, but encompasses any and all embodiments within the scope of thefollowing claims.

Therefore, what is claimed is:
 1. A casting machine for casting parts in a mold out of a metal using a metal feed stock, the machine comprising: a a processing cylinder formed in a thermally conductive block, said processing cylinder having a processing chamber and opposite first and second ends, the first end of the processing cylinder being configured to receive the metal feed stock; b an injector cylinder formed in the thermally conductive block adjacent the processing cylinder, the injector cylinder having a shooting pot coupled to the second end of the processing cylinder by a passage configured to permit feed stock to pass from the processing cylinder into the shooting pot, a nozzle coupled to the injector cylinder configured to couple to the mold; c a processing drive for driving the feed stock from the first end of the processing cylinder through the passage into the shooting pot, a heater thermally coupled to the processing cylinder, the heater and processing cylinder configured to heat the feed stock such that the feed stock becomes progressively more liquid as it passes from the first to the second end of the processing cylinder, and d an injector plunger coupled to an injector actuator for driving the plunger sufficiently to force the metal from the shooting pot through the nozzle and into the mold.
 2. The casting machine of claim 1 wherein the injector cylinder and the processing cylinder are positioned side by side.
 3. The casting machine of claim 2 comprising a plurality of processing cylinders surrounding the injector cylinder.
 4. A device for casting a part in a mold comprising a plurality of casting machines as defined in claim 1 coupled to said mold.
 5. The casting machine of claim 3 wherein the injector cylinder and the processing cylinders are all formed in a single thermally conductive block.
 6. The casting machine of claim 5 wherein each of the processing cylinders are coupled to the passage.
 7. The casting machine of claim 6 wherein the passage has a volume greater than the shooting pot.
 8. The casting machine of claim 1 wherein the processing drive comprises a processing plunger coupled to a processing actuator configured to drive the processing plunger in the processing cylinder between the first and second ends of the processing cylinder.
 9. The casting machine of claim 3 further comprising a distributor for distributing the feed stock from a hopper into each of the processing cylinders.
 10. The casting machine of claim 7 wherein the processing drive comprises a processing plunger for each processing cylinder coupled to a processing actuator configured to drive the processing plungers in the processing cylinders between the first and second ends of the processing cylinders.
 11. The casting machine of claim 10 wherein the processing drive further comprises a first member coupled to each of the processing plungers, the first member coupled to me processing actuator.
 12. The casting machine of claim 9 further comprising a distributor for distributing the feed stock from a hopper into each of the processing cylinders, the distributor comprising an annular member rotatably mounted to the block adjacent the first ends of the processing cylinders, the annular member having at least one finger dimensioned to spread the feed stock among the processing cylinders as the annular member rotates.
 13. The casting machine of claim 11 further comprising a distributor for distributing the feed stock from a hopper into each of the processing cylinders, the distributor comprising an annular member rotatably mounted to the block adjacent the first ends of the processing cylinders, the annular member having a plurality of fingers dimensioned to spread the feed stock among the processing cylinders, the annular member having a plurality of passages to permit the processing plungers to pass there through, the processing plunger drive being further configured to withdraw the plungers from the processing cylinders and away from the second member to permit the second member to rotate relative to the processing cylinders.
 14. A casting machine for casting parts in a mold out of a metal feed stock, the casting machine comprising; a a thermally conductive block; b a processing cylinder having opposite first and second ends formed in the block, the first end configured to receive the feed stock; c the block being thermally coupled to a heater, the heater, block and processing cylinder being configured to heat the feed stock such that the feed stock becomes progressively more liquid as it passes from the first to the second end of the processing cylinder; d an injector cylinder formed in the block adjacent the processing cylinder, the injector cylinder having a shooting pot and an injector plunger coupled to a nozzle, the shooting pot being coupled to the second end of the feed stock processing cylinder by a passage configured to permit the one way movement of heated feed stock from the processing cylinder into the shooting pot, the injector plunger configured to inject the heated feed stock through the nozzle into the mold.
 15. The casting machine of claim 14 comprising a plurality of processing cylinders formed in the block and surrounding the injector cylinder, each of the processing cylinders being coupled to the passage.
 16. The casting machine of claim 15 further comprising a processing drive for urging the feed stock through the processing cylinders, the processing drive comprising a processing plunger for each processing cylinder, the processing plungers coupled to a processing actuator for moving the processing plungers between the first and second ends of the processing cylinder.
 17. The casting machine of claim 16 further comprising a distributor for distributing the feed stock from a hopper into each of the processing cylinders, the distributor comprising at least one finger movably mounted to the block adjacent the first ends of the processing cylinders, and further comprising a finger actuator for moving the finger sufficiently to spread the feed stock among the processing cylinders.
 18. The casting machine of claim 17 further comprising a cap mounted onto the thermally conductive block adjacent the first ends of the processing cylinders, the cap configured to permit the processing and injection plungers to pass there through, the thermally conductive block having a mounting plate adjacent the mold and further comprising a compression actuator coupled to the cap and mounting plate for keeping the cap, the block and the mounting plate in compression.
 19. A machine for molding a part out of a feed stock, said device comprising: a a mold having a plurality of mold portions, each mold portion configured to mold a different portion of the part: b a plurality of molding units, each molding unit being coupled to one of said portions for molding said portion; c each molding unit comprising a thermally conductive block with a processing cylinder formed therein, said processing cylinder having opposite first and second ends, the first end configured to receive the feed stock; d the block being thermally coupled to a heater, the heater, block and processing cylinder being configured to heat the feed stock such that the feed stock becomes progressively more liquid as it passes from the first to the second end of the processing cylinder; e an injector cylinder formed in the block adjacent the processing cylinder, the injector cylinder having a shooting pot, an injector plunger and a nozzle, the nozzle being coupled to the mold portion, the shooting pot being coupled to the second end of the feed stock processing cylinder by a passage configured to permit the movement of heated feed stock from the processing cylinder into the shooting pot, the injector plunger configured to inject the heated feed stock through the nozzle and into the mold.
 20. The machine of claim 19 wherein the molding units each comprise a plurality of processing cylinders formed in the block and surrounding the injector cylinder, each of the processing cylinders being coupled to the passage.
 21. The machine of claim 20 wherein the molding units each further comprise a processing drive for urging the feed stock through the processing cylinders, the processing drive comprising a processing plunger for each processing cylinder, the processing plungers coupled to a processing actuator for moving the processing plungers between the first and second ends of the processing cylinder.
 22. The machine of claim 21 wherein the molding units each further comprise a distributor for distributing the feed stock from a hopper into each of the processing cylinders, the distributor comprising at least one finger movably mounted to the block adjacent the first ends of the processing cylinders, and further comprising a finger actuator for moving the finger sufficiently to spread the feed stock among the processing cylinders.
 23. The machine of claim 1 wherein the thermally conductive block is insulated
 24. The casting machine of claim 1 further comprising a mold cooler for removing heat from the mold, the mold cooler configured to transfer a portion of the heat removed from the mold to the feed stock before the feed stock enters the processing cylinder. 